Modular unit loading and unloading apparatus

ABSTRACT

A transport apparatus that can load and unload load carrying containers directly to and from the ground, to and from specially designed receivers or from and to portable support stands. The transport apparatus includes a tiltable trailer having longitudinal guide rails or surfaces that receive anti-friction devices of the load carrying containers. The tiltable trailer can be carried by a ground wheel support chassis and can be pivoted between a substantially horizontal travelling position and a backwardly-downwardly inclined position at which the rear portions of its longitudinal guide surfaces have been displaced toward the ground to a position above the ground where they can engage the anti-friction devices of a ground supported load carrying container.

CROSS-REFERENCE

The present application is related to my pending U.S. application Ser.No. 08/001,960, filed Jan. 1, 1993, entitled "Roll on Roll Off Device"now U.S. Pat. No. 5,490,753. This application is also related to U.S.application Ser. No. 08/200,958 filed on Feb. 24, 1994, entitled "ROLLON ROLL OFF DEVICE WITH A PORTABLE SUPPORT". Both of these applicationsare incorporated herein by this reference.

BACKGROUND OF THE INVENTION

This invention relates to a transport apparatus for vehicles that canload and unload modular containers or units directly from and to theground (fully ground bearing). Although the embodiment disclosed in thisapplication has the fully ground bearing capability it has theversatility to load and unload modular containers or units from fixed orpermanent receivers designed for this purpose or to load and unload toand from transportable support devices, such as is more completelydisclosed in the above referred to co-pending U.S. application Ser. Nos.08/001,960 and 08/200,958.

The modular container or unit to be transported can have various shapesand perform various functions. For example, it can be in the form of aspecialized container such as a food or drink package, a fire woodcontainer or a container for industrial parts. Other forms that themodular units could be are boat trailers, portable offices, fuel tanks,water tanks, cranes or an animal shelter. The transport apparatus couldbe a self propelled vehicle such as a vehicle designed specifically forthis purpose or a trailer that is towed for example by a pick-up truck.The transport apparatus could also be a towed trailer that has a selfpropelled winch mounted thereon. When the transport apparatus of thisapplication is used the modular container or units can be supporteddirectly on the ground or pavement and thus specially designed stands orreceivers for supporting the modular container or unit prior to loadingand for unloading to are not required. This is especially advantageousin unloading the modular container or unit, and retrieving empty modularcontainer or units since the point of delivery is often a remote sitethat does not have compatible specialized equipment.

U.S. Pat. No. 4,930,799, entitled TILTABLE TRAILER FOR MOTOR VEHICLES,ESPECIALLY PASSENGER CARS discloses an apparatus including a chassismade up of a front frame element and a rear element that is tiltablerelative to the front element. A winch is mounted on the front frameelement and includes a wire that extends rearwardly to a basic framewhich is a common part of a plurality of add-on units. The wire from thewinch extends over the free end of a pivotable arm that is connected tothe rear end of the frame element, such that the front end of the basicframe is elevated prior to be being pulled forward. When the basic frameis pulled forward it causes the pivotable arm to fold down. There is astop at the forward end of the frame element to stop forward movement ofthe basic frame and locking means, at the rear end of frame element forautomatically securing the basic frame to the frame element. A lever isdisclosed that is connected to the basic frame that causes the basicframe to move a distance from the frame element when the two areseparated.

The invention in prior art U.S. Pat. No. 4,930,799 is in the specialpivotable arm and lever that enable the apparatus to pick up and deliverthe basic frame to and from the ground. Although the special arms andlevers of the type that are disclosed in this prior art reference permitpick up from and delivery to the ground they add expense, weight andcomplexity to the device. Furthermore, the special pivotable arm andlever limits the versatility of the basic frame since they wouldinterfere if the basic frame were to be used with special designedreceivers or with portable support stands. However, a production modelof the trailer disclosed in U.S. Pat. No. 4,930,799 could be retrofitedto include the invention of this application. Furthermore, othercommercially available dump type trailers could be easily andinexpensively retrofited to use the invention of this application.

For the foregoing reasons, there is a need for a fully ground bearingapparatus for vehicles that can load and unload a modular container orunit from and to the ground, from and to special designed receivers orfrom portable support stands.

SUMMARY OF THE INVENTION

The present invention is directed to a transport apparatus thatsatisfies the need for a transport apparatus that can load and unloadfully ground bearing apparatus from and to the ground. The transportapparatus of this invention can also load and unload from and tospecially designed receivers or from and to portable support stands.

The transport apparatus consists of a tiltable trailer and a loadcarrying structure that can be loaded to or unloaded from the tiltabletrailer. The tiltable trailer has a ground wheel support chassis uponwhich is pivotally supported a tiltable frame that has longitudinalguide surfaces along each of its side portions. The longitudinal guidesurfaces being elevated from the base of the tiltable frame a givendistance. The tiltable frame can be pivoted between a substantiallyhorizontal travelling position and a backwardly-downwardly inclinedposition at which the rear portions of its longitudinal guide surfaceshave been displaced toward the ground to a location where they arespaced above the ground a distance that is less than said givendistance. The load carrying structure has ground engaging supports andanti-friction devices that define surfaces that are substantiallyhorizontal when said load carrying structure is supported on the ground.The surfaces defined by the anti-friction devices are spaced above theground a distance less than said given distance when the load carryingstructure is supported on the ground. The load carrying structure issupported on and can be displaced along the longitudinal guide surfacesof the tiltable frame element. A winch including a cable is carried bythe ground-wheel supported chassis, with the free end of the cable beingconnectable to said load carrying structure for moving it along thetiltable frame element.

In the preferred embodiment an electrically controlled hydraulicmechanism is used to pivot the tiltable frame relative to the groundwheel support chassis and an electrically controlled winch is used tomove the load carrying structure along the inclined tiltable frameelement. Each of these electrically controlled systems are operated byremote controls. The remote controls have a range of about 50 feet whichenables an operator to be a safe distance away from the transportapparatus when the modular units are being loaded or unloaded. Theremote control further enables an operator to be at a location where anoverview of the equipment and its surroundings is possible.

The tiltable trailer of this application, in addition to use as one ofthe components of the loading and unloading apparatus of this inventioncan be used alone as a dump trailer.

For the foregoing reasons there is a need for a tiltable trailer thatcan pick up a load and deliver a load directly from and to the ground orfrom and to specially designed receivers or from and to portablesupports stands.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of an embodiment of the invention with thetiltable frame element slightly elevated.

FIG. 2 is the first view in a series of side views of an embodiment ofthe transport apparatus.

FIG. 3 is the second view in a series of side views of an embodiment ofthe transport apparatus.

FIG. 4 is the third view in a series of side views of an embodiment ofthe transport apparatus.

FIG. 5 is the fourth view in a series of side views of an embodiment ofthe transport apparatus.

FIG. 6 is the fifth view in a series of side views of an embodiment ofthe transport apparatus.

FIG. 7 is the sixth and final view in a series of side views of anembodiment of the transport apparatus.

FIG. 8 is an enlarged isolated view of one embodiment of the loadcarrying structure.

FIG. 9 is a view of a roll on roll off mechanism that utilizes portablejacks or supports, to support the load carrying structure at a locationspaced above the ground, that can be used with the transport apparatusdisclosed herein.

FIG. 10 is another view of the roll on roll off mechanism seen in FIG.9.

FIG. 11 shows a receiver, that can be permanent or portable, that can beused with the transport apparatus disclosed herein.

FIG. 12 is an isolated rear view of the tiltable frame element.

FIG. 13 is an isolated rear view of the tiltable frame element with oneembodiment of the load carrying structure supported thereon.

FIG. 14 is an isolated rear view of the tiltable frame element withanother embodiment of the load carrying structure supported thereon.

FIG. 15 is side view of the embodiment of the invention seen in FIG. 1without a load carrying structure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

There is shown in FIG. 1 a side view of the preferred embodiment of thetransport apparatus 10. The transport apparatus 10 is made up of atiltable trailer 20 and a load carrying structure 40. The tiltabletrailer 20 includes a ground wheel support chassis 28 having groundengaging wheels 29 and a tiltable frame element 26. The tiltable frameelement 26 has longitudinal guide surfaces 22 on each side thereof and awinch 24 and tool and accessory box 23 at its forward end. Thelongitudinal guide surfaces 22 are in the shape of tracks that functionto retain the anti-friction devices. The tiltable frame element 26 is aweldment of tubular members and sheet material and thus provides asturdy structure that can support substantial loads. The sides of thetiltable frame is constructed of longitudinal tubes, such as bottomlongitudinal tube 21 which has a flat upper surface and vertical post31. The tiltable frame element 26 is pivotally connected to the groundwheel support chassis 28 along a hinge axis 30. A pair of three linkarrangements 32 are connected at their free ends to the tiltable frameelement 26 and the ground wheel support chassis 28. Hydraulic cylinders34, anchored at their cylinder ends on the ground wheel support chassis28 are connected at their rod ends to each of the hinges 32. It shouldbe noted that there is a three link arrangement 32 and a hydrauliccylinder 34 on each side of the ground wheel support chassis 28. Whenthe hydraulic cylinders 34 are expanded the tiltable frame element 26 ispivoted about hinge axis 30 toward its lowered or horizontal positionand when contracted tiltable frame element 26 is pivoted about hingeaxis 30 toward its raised or elevated position. Conventional hydraulicfluid pumps, storage batteries and control mechanisms are carried by theground wheel support chassis 28 and function to control the flow ofhydraulic fluid to and from the hydraulic cylinders 34. Conventionalelectronic controls are provided for actuating the control mechanismsfor the hydraulic cylinders 34. The electronic controls can be locatedin the cab of a self propelled vehicle that is used to tow the transportapparatus 10 or hand held remote controls can be used. Conventionalremote controls have a range of about 50 feet which enables an operatorto control the tiltable frame element 26 from a safe distance and from avantage point where the operator has an overview of the entire operatingarea.

The load carrying structure 40 has a set of anti-friction devices 42 oneach side thereof and ground engaging supports 44 at the front and backthereof. The anti-friction devices 42 are dimension and located suchthat they ride in grooves formed in the longitudinal guide surfaces 22.

A winch 24, mounted at the forward end of tiltable frame element 26,functions to wind in and out a cable 36 that is connected to loadcarrying structure 40. When winch 24 is engaged the load carryingstructure 40 moves longitudinally along the tiltable frame element 26.Control mechanisms or remote controls are provided for operating thewinch 24. When remote controls are used an operator can control both thepivoting movement of tiltable frame element 26 and the winch operationfrom a safe location where an overview of the operating area ispossible.

When the load carrying structure 40 is positioned in its full forwardposition member 37, that is secured to its forward portion, overlies alocking member 38 that is carried by the forward portion of tiltableframe element 26. The member 37 and the locking member 38 have aperturesformed therein that become aligned when the load carrying structure 40reaches its full forward position. Gravity pins 39 are inserted throughthe aligned apertures to lock the load carrying structure 40 in its fullforward position on the tiltable frame element 26. With the gravity pins39 in place the tiltable frame element 26 can be raised and the loadcarrying structure 40 will remain in its full forward position relativeto the tiltable frame element 26. This arrangement could be used when itis desired to dump the load out of the rear of load carrying structure40 rather than sperate the load carrying structure from the tiltableframe element 26. However the main function of gravity pins 39 is tofunction as a safety lock mechanism to insure that the load carryingstructure 40 will not accidently roll off the tiltable trailer 20 duringtransport of the transport apparatus 10.

The ground wheel support chassis 28 has a pair of forward groundengaging jacks 54 and a pair rear ground engaging jacks 56 which can belowered to anchor the ground wheel support chassis 28 in place. Thisrelieves the springs and axles from the burden of supporting heavy loadsduring loading and unloading operation and can be of particularimportance when heavy loads are being manipulated or the ground is notsolid.

A manual support mechanism 58, is carried by ground wheel supportchassis 28, that includes a stop 60 in the form of a plate that extendsinwardly toward the side of tiltable frame element 26 and overlays theflat upper surface of longitudinal tube 21. Manual support mechanism 58functions to support the tiltable frame element 26 in a raised positionrelative to the ground wheel support chassis 28. When the tiltable frameelement 26 reaches its maximum inclined position the bottom surface ofstop plate 60 engages the upper flat surface of longitudinal tube 21,thus providing a mechanical stop preventing further elevation of thetiltable frame element 26. At this time a lever type stop 62 can bemanually repositioned such that it engages the bottom flat surface oflongitudinal tube 21. Thus, stop provides a mechanical stop preventingthe lowering of tiltable frame element 26. The stops 60 and 62, whenfunctioning, also relieve stress on hydraulic cylinder 34. This isparticularly important when a heavily loaded load carrying structure 40is being pulled up the inclined tiltable frame element 26. Without themanual support mechanisms 58 the force of the load is transferred tohydraulic cylinder 34 which could be damaged. When the tiltable frameelement 26 is raised to receive a load carrying structure 40, stop 60 isengaged to prevent inclination beyond the designed maximum and stop 62is manually engaged to support the tiltable frame element 26 fromdownward movement. This provides a mechanical support to hold thetiltable frame element 26 in the inclined position and relieves thestresses from the hydraulic cylinder 34.

Referring now to FIG. 12 which is a rear view of the tiltable frameelement 26. In this view the base 27 and it rear end portion 25 can beseen. The longitudinal guide surfaces 22 are elevated, a given distance,above the base 27. In this view a second set of longitudinal guidesurfaces 122 are identified. Guide surfaces 122 are located at a levelbelow guide surfaces 22.

In FIG. 13 the load carrying structure 40 has been added to the view ofthe tiltable frame element 26 seen in FIG. 12. It should be noted thatthe bottom surface of load carrying structure 40 does not contact thebase 27 and the entire weight of the load carrying structure 40 issupported by the anti-friction devices 42 that ride in the longitudinalguide surfaces 22.

The roll on roll off feature of the transport apparatus 10 will now bediscussed with reference to the series of drawings identified as FIGS.2-7. It should be noted that because of the small scale of the thesedrawings some of the details, such as the hinge 32, that are seen inFIG. 1 are not included in these drawings.

In FIG. 2 the tiltable frame element 26 is in its horizontal or fullylowered position. This is the transport position and prior to transportthe gravity pins 39 should be inserted to lock the load carryingstructure 40 to the tiltable trailer 20.

When it is desired to roll the load carrying structure 40 off thetiltable trailer 20 at a delivery destination the gravity pins 39 areremoved and the hydraulic cylinders 34 are contracted which causes thethree link arrangement 32 to begin opening and the tiltable frameelement 26 to begin pivoting up about hinge axis 30.

The tiltable frame element 26 is shown in FIG. 3 at a position where ithas been pivoted up about 10°. The load carrying structure 40 has, inFIG. 3, moved rearwardly from its home position shown in FIG. 2. Thewinch 24 is actuated to unwind cable 36 in the direction which permitsthe load carrying structure 40 to roll in response to gravity down thelongitudinal guide surfaces 22 of the tiltable frame element 26.

As seen in FIG. 4 the elevation of tiltable frame element 26 has beenincreased to about 30° and the load carrying structure 40 has rolleddown the longitudinal guide surfaces 22 to the point where the rearground engaging supports 44 make initial contact with the ground.

In FIG. 5 the tiltable frame element 26 remains at about a 30° elevationand the load carrying structure 40 has rolled further down thelongitudinal guide surfaces 22. The rear ground engaging supports 44,which are in the form of rollers or wheels, permit the bottom rearcorner of the load carrying structure 40 to roll rearwardly relative tothe transport apparatus 10. It should be noted that in FIG. 5 only theforward most anti-friction devices 42 remain in engagement with thelongitudinal guide surfaces 22 which minimizes the frictional resistancebetween the anti-friction devices 42 and the longitudinal guide surfaces22. If the friction between the rear ground engaging supports 44 and theground is to great to permit gravity to roll the load carrying structure40 back the transport apparatus 10 can be driven or pulled forward.

As seen in FIG. 6 the tiltable frame element 26 remains at an elevationof about 30° and the load carrying structure 40 has rolled further downthe longitudinal guide surfaces 22 and further to the rear of transportapparatus 10.

In FIG. 7 the tiltable frame element 26 has been elevated to about 40°and the load carrying structure 40 is now supported on the ground byboth its front and rear ground engaging supports 44. At this point thecable 36 can be disconnected from the load carrying structure 40 and theempty transport apparatus 10 moved away from the load carrying structure40.

When it is desired to pick up the load carrying structure 40 from itsfully ground bearing or supported position, the empty transportapparatus 10 is backed up to the load carrying structure 40 to thepositions as shown in FIG. 7 at which the forward most anti-frictiondevices 42 of the load carrying structure 40 are in engagement with thelongitudinal guide surfaces 22 of the tiltable frame element 26. Whenengagement of the forward most anti-friction devices 42 with thelongitudinal guide surfaces 22 has been achieved the winch 24 isactivated in the direction to wind in the cable 36 and begin rolling theload carrying structure 40 up the inclined longitudinal guide surfaces22. The sequence of events shown in FIGS. 2-7 is reversed until thetiltable frame element 26 is in its horizontal or fully lowered positionand the load carrying structure 40 is in its home or fully forwardposition. When the load carrying structure 40 has been rolled up toabout the position shown in FIG. 4 the tiltable frame element 26 can belowered to its horizontal position and the load carrying structure 40pulled by winch 24 to its full forward position. At the full forwardposition the gravity pins 39 are inserted to lock the load carryingstructure 40 in place on the tiltable frame element 26.

Referring now to FIG. 8 which shows the load carrying structure 40isolated and at a larger scale. The forward most anti-friction devices42 are constructed of cast iron or steel wheels such that there is nocushion or compression between the load carrying structure 40 and thelongitudinal guide surfaces 22. This minimizes the frictional resistancebetween the forward most anti-friction devices 42 and the longitudinalguide surfaces 22. However, the rear most anti-friction devices 42 andthose between the forward most and rear most have rubber surfaces andhave a slightly larger diameter than the forward most ground engagingsupports. As a result when the tiltable frame element 26 is in itshorizontal or transport position the load carrying structure 40 issupported on the longitudinal guide surfaces 22 by the larger cushionedanti-friction devices 42. This not only cushions the ride when in thetransport position but also results in a much quieter ride.

Also disclosed in FIG. 8 are sockets 46 which can be used in cooperationwith portable jacks to store the load carrying structure 40 at a levelabove the ground. A detailed disclosure of a system of this type isdisclosed in my above identified co-pending application Ser. No.08/200,958. FIGS. 9 and 10 are FIGS. taken from my co-pendingapplication Ser. No. 08/200,958 minus the reference numbers from thatapplication. FIG. 9 corresponds to FIG. 3 after the tiltable frameelement 26 has been returned to its horizontal or lower most position.Portable jacks 48 of the type shown in FIGS. 9 and 10 are secured to theload carrying structure 40 through sockets 46 to thus store the loadcarrying structure 40 at a position elevated from the ground.

FIGS. 9 and 10 are illustrations of another embodiment of theapplicant's invention. In the illustrations of this embodiment thetransport vehicle is shown as a pick up truck however the inventioncould be used with any type of vehicle or transport device. For examplethe transport vehicle could be a small trailer, a large trailer pulledby highway tractor, a flat bed truck, a small or large van, a train, aship, a barge or an airplane. As seen in FIGS. 9 and 10 the container 40includes two sets of rollers 42 that are secured to horizontal bottomsupport surfaces such that they are horizontal to each other. Thetransport vehicle includes a pair of elongated flat support surfaces 22that extend horizontal to the ground and parallel to each other. Theflat support surfaces 22 are unencumbered from above and are located onthe transport vehicle such that they function to support the container40 through the rollers 42. The container 40 is supported on thetransport vehicle at a fixed elevation above the ground such that thebottom surface of the container is spaced from and not in contact withthe bottom surface of the transport vehicle. The sets of rollers 42 andthe flat support surfaces 22 function as cooperating anti-frictionmechanisms that will permit the container 40 to be rolled on and off thetransport vehicle with little effort. The transport vehicle andcontainer 40 include cooperating anchor devices that function to securethe container 40 in place on the transport vehicle. Anchoring devicessuch as gravity pins 39 as shown in FIG. 1 could be used for thispurpose.

In this embodiment independent support 48 for the container 40 aretransported with the container and transport vehicle. It is importantthat the portable independent support is capable of supporting thecontainer at the same elevation above the ground as it will be or wassupported on the transport vehicle so as to insure a smooth relativemovement therebetween. In this respect it should be noted that ifmultiple transport vehicles are used their support surfaces may not belocated at equal elevations above the ground. For this reason theindependent supports 48 used in this embodiment are in the form of jacksthat can be adjusted to support the container at a selected elevationabove the ground.

As seen in FIG. 9 sockets 46 are provided near the bottom of thecontainer 40 for receiving the jacks 48.

In FIG. 10 the transport vehicle has been driven forward or thecontainer 40 has been rolled rearwardly to complete the transfer of thecontainer from the transport vehicle to the jacks 48.

The transport apparatus 10 disclosed herein also has the versatility ofusing stationary storage platforms of the type disclosed in my aboveidentified co-pending patent application Ser. No. 08/001,960. FIG. 11 isa Figure that has been reproduced, without the old reference numbers,from application Ser. No. 08/001,960. Platforms of the type 50 disclosedin FIG. 11, are provided at the regular pick up and delivery locations.A load carrying structure 40 can be loaded from a platform 50 to atiltable frame element 26, that is horizontal, by sliding ithorizontally along the elongated flat support surfaces 52 on to thelongitudinal guide surfaces 22 of the horizontal tiltable frame element26. When the transport vehicle has spring loaded axles, as would beexpected in the pick up truck disclosed in FIGS. 9 and 10, thelongitudinal guide surfaces 22 would begin to lower as weight istransferred to the transport vehicle. This can be accommodated for byadjusting the jacks located at the front of the platform 50. The slidingoperation is reversed when it is desired to unload a load carryingstructure 40 from a horizontal tiltable frame element 26 to a platform50. The opposite is also true when unloading a heavy loaded container40, of the type seen in FIG. 9 to a stationary platform 50 of the typeseen is FIGS. 11. When such an operation is accomplished the guidedsurfaces 22 will raise up as weight is removed from the transportvehicle. When this occurs the jacks on the front of platform 50 must beexpanded to insure that the surfaces 22 and 52 remain on the same plane.

Loading and unloading from a platform 50, of the type illustrated inFIG. 11, is a much simpler and faster procedure that loading andunloading from the ground. Thus, this is a valuable and useful optionthat is available with the transport apparatus of this invention.

Referring now to FIG. 14 wherein another embodiment of the load carryingstructure is disclosed. The load carrying structure 140 seen in thisFigure is a flat bed carrier having a flat bottom surface 142 and afront vertical wall 146. It should be noted that this embodiment theanti-friction devices 144 ride in the second set of longitudinal guidesurfaces 122 rather than the guide surfaces 22. This lowers the centerof gravity of the loaded load carrying structure 140 and stabilizes thetransport apparatus 10.

FIG. 15 is a side view of the embodiment of the invention seen in FIG. 1without the load carrying structure 40. When the load carrying structure40 is removed from the transport apparatus 10 the tiltable frame element26 can function as a dump trailer. The tiltable frame element 26 has asolid bottom, front and side walls. All that needs to be added to thisstructure is a tail gate 70 that can for example be hinged 72 along itsbottom edge.

It is intended that the accompanying drawings and the foregoing detaileddescription is to be considered in all respects as illustrative and notrestrictive, the scope of the invention is intended to embrace anyequivalents, alternatives, and/or modifications of elements that fallwithin the spirit and scope of the invention, and all changes which comewithin the meaning and range of equivalency of the claims are thereforeintended to be embraced therein.

What is claimed is:
 1. A tiltable trailer and load carrying structurecomprising:a ground-wheel supported chassis; a tiltable frame elementincluding a base having front and rear end portions and longitudinalside portions, said tiltable frame element including longitudinal guidesurfaces along each of said longitudinal side portions, saidlongitudinal guide surfaces being elevated from said base a givendistance, said tiltable frame element being pivotally mounted on saidground-wheel supported chassis such that it can be pivoted between asubstantially horizontal travelling position and a backwardly-downwardlyinclined position at which said rear portion of said base has beendisplaced toward the ground such that the rear most portions of saidlongitudinal guide surfaces are spaced from the ground a distance lessthan said given distance; a load carrying structure including groundengaging supports and anti-friction devices that define surfaces thatare substantially horizontal when said load carrying structure issupported on the ground, said surfaces defined by said anti-frictiondevices being spaced above the ground a distance less than said givendistance when the load carrying structure is supported on the ground,said load carrying structure being adapted to be supported on anddisplaceable along said longitudinal guide surfaces of said tiltableframe element; and a winch including a cable carried by said tiltableframe element, said cable being connectable to said load carryingstructure for conveying said load carrying structure along said tiltableframe element, when said tiltable frame element is in its inclinedposition and the rear most portion of said longitudinal guide surfacesare spaced from the ground a distance less than said given distance,from a position in which the load carrying structure is supported on theground behind said tiltable frame element, to a position coinciding withthat of said tiltable frame element.
 2. The invention as set forth inclaim 1 wherein;locking devices are carried by said load carryingstructure and said tiltable frame element to lock said load carryingstructure to said tiltable frame element.
 3. The invention as set forthin claim 1 wherein:first anti-friction devices are located at theforward most position of the surfaces defined thereby such that saidfirst anti-friction devices overlie said rear most portions of saidlongitudinal guide surfaces that are spaced from the ground a distanceless than said given distance when said tiltable frame element is in itsbackwardly-downwardly inclined position.
 4. The invention as set forthin claim 1 wherein:the rear most ground engaging supports of said loadcarrying structure being wheels that will support the rear of said loadcarrying structure on the ground as its forward end is being pulled upthe backwardly-downwardly inclined longitudinal guide surfaces.
 5. Theinvention as set forth in claim 1 wherein:said winch includes a cablehaving a hook at its distal end and said load carrying structureincludes a hook receiving device at its front end that is adapted toreceive said hook.
 6. The invention as set forth in claim 1 wherein:saidground-wheel supported chassis includes adjustable ground engaging jacksthat can be lowered to immobilize said ground-wheel supported chassiswhen loading and unloading said load carrying structure.
 7. A tiltabletrailer and load carrying structure comprising:a ground-wheel supportedchassis; a tiltable frame element pivotally secured to said ground-wheelsupported chassis about a transverse pivot axis such that it can bepivoted between a substantially horizontal travelling position and abackwardly-downwardly inclined position; said tiltable frame elementincluding a base having front and rear end portions and longitudinalside edges, upwardly extending side portions secured to said base alongsaid longitudinal side edges and a front vertical wall that is securedto the front end portion of said base and extend upwardly therefrom,wherein the improvement comprises:said tiltable frame element beingpivotally mounted on said ground-wheel supported chassis between saidfront and rear end portions of said base such that when the front endportion of the base is pivoted up the rear end portion of said base willpivot down and be displaced toward the ground to a location below saidtransverse pivot axis pivot axis; said tiltable frame element includeslongitudinal guide surfaces along the tops of each of said longitudinalside portions, said longitudinal guide surfaces being elevated from saidbase a given distance; a load carrying structure including groundengaging supports and anti-friction devices that define surfaces thatare substantially horizontal when said load carrying structure issupported on the ground, said surfaces defined by said anti-frictiondevices being spaced above the ground a distance less than said givendistance when the load carrying structure is supported on the ground,said load carrying structure being adapted to be supported on anddisplaceable along said longitudinal guide surfaces of said tiltableframe element; and a winch including a cable carried by said tiltableframe element, said cable being connectable to said load carryingstructure for conveying said load carrying structure along said tiltableframe element, when said tiltable frame element is in its inclinedposition and the rear most portion of said longitudinal guide surfacesare spaced from the ground a distance less than said given distance,from a position in which the load carrying structure is supported on theground behind said tiltable frame element, to a position coinciding withthat of said tiltable frame element.
 8. The invention as set forth inclaim 7 wherein;locking devices are carried by said load carryingstructure and said tiltable frame element to lock said load carryingstructure to said tiltable frame element.
 9. The invention as set forthin claim 7 wherein:first anti-friction devices are located at theforward most position of the surfaces defined thereby such that saidfirst anti-friction devices overlie said rear most portions of saidlongitudinal guide surfaces that are spaced from the ground a distanceless than said given distance when said tiltable frame element is in itsbackwardly-downwardly inclined position.
 10. The invention as set forthin claim 7 wherein:the rear most ground engaging supports of said loadcarrying structure being wheels that will support the rear of said loadcarrying structure on the ground as its forward end is being pulled upthe backwardly-downwardly inclined longitudinal guide surfaces.
 11. Theinvention as set forth in claim 7 wherein:said winch includes a cablehaving a hook at its distal end and said load carrying structureincludes a hook receiving device at its front end that is adapted toreceive said hook.
 12. The invention as set forth in claim 7wherein:said ground-wheel supported chassis includes adjustable groundengaging jacks that can be lowered to immobilize said ground-wheelsupported chassis when loading and unloading said load carryingstructure.